WO 03/033058 discloses a hand-held device powered by an internal combustion engine.
The document discloses inter alia a device, especially a device suitable for delivering a dose of medicament to a subject, wherein there is a first combustive event to perform the intended task (i.e. deliver the medicament) and a second combustive event which is used to compress a successive charge of fuel and combustion-supporting gas for a subsequent cycle of operation, such that the device is essentially self-priming. The two combustive events take place in separate combustion chambers.
The only embodiment of such a device described in detail is an arrangement whereby a priming combustion event in a priming combustion chamber causes the movement of a work piston into a primed position within a main combustion chamber, and a combustion event in the main combustion chamber causes return movement of a priming piston as well as acting on the work piston.
The present invention relates to a device which is generally similar to that disclosed in WO 03/033058 but differs therefrom in a number of respects, e.g. whilst the device of the present invention has two combustion chambers (a priming combustion chamber and a main combustion chamber), which typically communicate via one or more apertures usually incorporating associated one-way flow valve means, a combustion event in the priming combustion chamber does not cause movement of the work piston and wherein a combustion event in the main combustion chamber does not cause movement of the priming piston.
In particular, in the prior art arrangement the priming and work pistons are accommodated, and move within, a common bore (in which the respective travels of the priming and work pistons overlap) between the priming and main combustion chambers. In contrast, in the device of the present invention the priming piston and work piston are accommodated and move within separate bores and do not share a common bore.
The content of all publications cited is specifically incorporated herein by reference.